To achieve complete resection of metastatic colonic carcinoma in the liver and lung, thoracolaparotomy-assisted simultaneous resection was attempted in a 60-year-old male patient who had previously undergone sigmoidectomy for primary sigmoid colon carcinoma. A solitary liver metastasis was observed in segment 7 and a solitary lung metastasis was located in segment 6 of the right lower lung. Simultaneous resection was attempted and, in the left lateral position, a thoraco-laparotomy with oblique incision was made in the right seventh intercostal space. Both tumors could be palpated under a good operative view. A partial hepatectomy was performed followed by a segmental resection of the lung. A chest drainage tube was inserted for two postoperative days. The patient had no remarkable complications including pulmonary complication after surgery and was discharged at day 20 post-operation. For metastatic tumors simultaneously located in the right subphrenic part of the liver and the lower part of the right lung, thoraco-laparoscopy-assisted complete resection is a safe and useful option to achieve curative treatment.